Chapter 10 Muscular System Gross Anatomy. General Principles

Transcription

1 Chapter 10 Muscular System Gross Anatomy 10-1 General Principles Tendons: attach muscles to bones Aponeurosis: a very broad tendon Muscle terminology Origin or head: muscle end attached to more stationary of two bones Insertion: muscle end attached to bone with greatest movement Belly: largest portion of the muscle between origin and insertion Agonist: muscle that, when it contracts, causes an action Antagonist: a muscle working in opposition to agonist Synergists: muscles that work together to cause a movement Prime mover: plays major role in accomplishing movement Fixators: stabilize joint/s crossed by the prime mover; prevent movement of the origin of the prime mover

2 Muscle attachment 10-3 Muscle Types

3 Examples of Muscle Shapes 10-5 Nomenclature Muscles are named according to: Location: pectoralis gluteus, brachial Size: maximus, minimus, longus, brevis Shape: deltoid, quadratus, teres Orientation: rectus Origin and insertion: sternocleidomastoid, brachioradialis Number of heads: biceps, triceps Function: abductor, adductor, masseter

4 Muscle Movements Muscles and their tendons and bones act together as lever systems to move either parts of the body or the whole body. Muscle contractions are a pull or force by relative positions of Lever: rigid shaft or bone Fulcrum: pivot point or joint Weight or resistance (force of gravity either in the form of the weight of the body parts or the weight of an object being lifted, pulled, or pushed) 10-7 Muscle Anatomy: Anterior View

5 Muscle Anatomy: Posterior View 10-9 Head and Neck Muscles Flexion: muscles deep within the neck along the anterior margins of the vertebral bodies Extension: posterior neck muscles attached to occipital bone Rotation and abduction: lateral and posterior groups Examples: sternocleidomastoid, trapezius, splenius muscles

6 Muscles of Facial Expression Cutaneous; origin and insertion in the superficial fascia. Confined primarily to head and neck. Move the skin; some act as sphincters. Examples: orbicularis oris, orbicularis oculi, platysma Tongue Movements Important in speech: changes shape Swallowing Moves food around in mouth Holds food in place during grinding Pushes food up to palate and back toward pharynx (Intrinsic: entirely within Extrinsic: change in shape and movement)

7 Muscles of Larynx Extrinsic Muscles of the Eye Rectus muscles: insert on sclera anterior to center of sphere. Move eyeball and thus pupil laterally, superiorly, inferiorly, and medially Oblique muscles: insert onto the posterolateral margin of the eyeball and both laterally deviate the eyeball. The superior oblique passes through a pulley-like trochlea

8 Muscles that Move the Vertebral Column Muscles that extend, laterally flex, and rotate the vertebral column. Used to produce erect posture Divided into deep and superficial groups (Deep group: from vertebra to vertebra Superficial group extend from vertebrae to ribs) Thoracic Muscles Involved in breathing Four groups associated with rib cage Scalenes: elevate first two ribs during inspiration External intercostals: elevate the ribs Internal intercostals: depress ribs during expiration Transversus thoracis: depresses ribs during expiration Diaphragm: major movement of inspiration. Flattens during contraction and increases the volume of the thoracic cavity

9 Flex and rotate vertebral column, decrease volume of abdominal and thoracic cavities Aid in forced expiration, vomiting, defecation, urination, childbirth Crossing pattern of muscles adds strength to abdominal wall to support organs Abdominal Wall Abdominal Wall Rectus Abdominis Flexes vertebral column External abdominal oblique: flexes and rotates abdomen Internal abdominal oblique: flexes and rotates abdomen Transversus abdominis: compresses abdominal wall

10 Scapular Movements Muscles that attach the upper limb to the body and move or stabilize the scapula and clavicle. Originate on the axial skeleton. Trapezius, levator scapulae, rhomboideus, serratus anterior, pectoralis minor Arm Movements Muscles that attach arm to thorax: pectoralis major, latissimus dorsi Deltoid and pectoralis major both act as flexors and extensors of the shoulder Deltoid abducts and medially and laterally rotates arm

11 Rotator Cuff Primary muscles holding humerus in the glenoid cavity Form a cuff or cap over the proximal humerus Involved in flexion, extension, abduction, adduction, rotation and circumduction Infraspinatus, subscapularis, supraspinatus, teres minor Forearm Movement Movements at the elbow Extension: triceps brachii and anconeus Flexion: biceps brachii, brachioradialis, and brachialis Supination and pronation: Supination: supinator and biceps brachii Pronation: pronator quadratus and pronator teres

12 Wrist, Hand, and Finger Movements Muscles on anterior surface of forearm: flexion as well as abduction and adduction of the wrist. Muscles on posterior surface of forearm: extension and abduction. Retinacula- bands of deep fascia which hold tendons of muscles of forearm, blood vessels, and nerves close to wrist. Flexor retinaculum (transverse carpal ligament): on the flexor surface Extensor retinaculum (dorsal carpal ligament): on the extensor surface Intrinsic Muscles of the Hand Originate and insert in hand

13 Originate on coxa; insert onto femur Anterior, posterolateral, deep Anterior: flex hip. Iliacus and psoas major often referred to as iliopsoas since they share a tendon of insertion Posterolateral: gluteals and tensor fasciae latae Extension of thigh Deep: thigh rotators Thigh Movement Leg Movements Quadriceps femoris: anterior surface of thigh Extension of the leg at the knee. Rectus femoris also flexes the hip. Insert by common tendon (patellar tendon) on and around the patella Patellar tendon extends from patella to tibial tuberosity Sartorius: flexes hip and knee, laterally rotates thigh Medial thigh muscles: adduction Posterior thigh muscles: hamstrings. Flexion and rotation of the knee

14 Muscles that Move the Leg Ankle, Foot, and Toe Movements Extrinsic foot muscles Three leg compartments Anterior compartment: extensors involved in dorsiflexion and eversion/inversion of foot; extension of toes. Dorsiflex foot, extend toes. Lateral compartment: plantar flexion and eversion. Posterior compartment- Superficial muscles (plantar flexion) have common tendon of insertion called the calcaneal (Achilles) tendon. Gastrocnemius, plantaris Deep muscles: plantar flex and invert foot

15 Extrinsic Muscles of the Foot Extrinsic Muscles of the Foot

16 Intrinsic Muscles of the Foot Analogous to intrinsics of hand, but serve in support and locomotion Flexion, extension, abduction and adduction of toes Deep fascia forms plantar aponeurosis